The blaze, broke out at J&J Ironworks, a one-story brick commercial building in Queens, at about 6 p.m. Monday, according to a Fire Department spokesman. About 200 firefighters were at the scene throughout the evening.

Fire Deputy Chief Gregory Rup said that four firefighters were burned when the building’s roof collapsed on them. One sustained serious burns to his face, another a back injury and two others were treated and released.

There was no one inside the factory when the fire started. The cause of the fire is unknown at this time.